Black-headed Gull Chroicocephalus ridibundus

(last update: 3-04-2011)

Below: Black-headed Gull, December 24, 2002, Amsterdam, The Netherlands.

First-calendar year Black-headed Gull in advanced first-winter (formative) plumage. During the post-juvenile moult, normally all feathers are replaced except those on the wings and in the tail. The body and head turn completely white, leaving a head pattern similar to adults (with a black ear spot and faint bars from ear to ear and eye to eye across the head). The legs turn orange and the bill orange with a white tip.

This individual displays an unusual advanced moult, in which the majority of the wing coverts and all of the tertials have been replaced by gray, second-generation feathers. Aging this individual is done based on the orange legs, orange bill with black tip, first-generation primaries and dark tail band (not visible in this image).